'70 Duraspark conversion - need resistor wire?

[redstone65]

Background here.

The wiring on this seems pretty straightforward from my reading. The ICM box needs full 12v to the red wire during START/RUN. And, full 12v to the white wire during START only. I read that the green wire outputs around 7 volts to the coil. So, I'm guessing the ICM itself handles reducing the voltage to the coil, so that the pink resistor wire can be bypassed. Is that correct?

[sargentrs]

With the Duraspark, there is no resistor. Full 12v on the red wire from the 2 prong plug on the box. The white wire is there to retard your timing a hair to make it easier for your engine to turn over when starting. It's a "signal" from the solenoid to the ICM that says "Hey!.. he's cranking the engine, retard the timing!" When you release the key after starting the signal switches off and the ICM advances the timing back to run mode. I recommend installing a relay. You can use the original green/red wire as the "trigger" for the relay and leave your original wiring intact. https://youtu.be/m88xAflUotM

[redstone65]

That's a tremendous help. Thank you for creating that Randy. Much appreciated.

[Ranchero50]

If the white wire is wired to the ignition "on" it'll nuke the modules. BTDT...

[sargentrs]

If the white wire is wired to the ignition "on" it'll nuke the modules. BTDT...

Should be to the S terminal on the solenoid, right Jamie?

[redstone65]

What size relay are you using? 30 amp?

[sargentrs]

Yep. 30 amp.

[redstone65]

Randy, should the original (brown) wire connected to the solenoid “I” terminal be removed in your setup? I have everything wired up according to your schematic but for some reason I’m getting12v to the coil(+) even with the key in the OFF position.

I ran out of daylight today but I plan to take a look at the schematics tomorrow and see what I can trace out.

[sargentrs]

Did you install a relay to power everything and are you using the original wire to the coil to trigger it? I always leave all my original wiring in place at the solenoid.

[redstone65]

Here is my drawing of how I wired it up according to my understanding of your drawing. Maybe you can spot something:



I actually re-checked it last night and now it was NOT giving 12v in the OFF position. There is clearly a short somewhere since I also noticed last night that both tail lights (headlights are off) stay lit all the time when the battery is connected. Switch, or no switch.

[sargentrs]

Yep, that's about the way I did it. Only difference is I went straight from the battery to the relay, istead of coming off the solenoid. I already had aftermarket bolt on battery cables so I just came off one of the clamp bolts with a 1/4" ring terminal spliced on the inline fuse pigtail. Is she running?

[redstone65]

Yep, it fired up and ran. Then it wouldn't turn off. . Pulled the key out but it wouldn't stop running. That's when we looked at the voltage on the coil and saw it had 12v with the key out. But, then last night it didn't. So, I'm head scratching at this point.

[sargentrs]

I accidently got my wires backward on the solenoid once. Freaked me out! Then it was like...DUH! Don't rule out a bad solenoid. Many are bad right out of the box. Glad she runs!

[redstone65]

I accidently got my wires backward on the solenoid once. Freaked me out! Then it was like...DUH! Don't rule out a bad solenoid. Many are bad right out of the box. Glad she runs!

Thanks Randy. Ive heard some are bad new. I’m suspect of the voltage regulator also since it’s new. As soon as I nail it down I’ll post back for posterity.

[redstone65]

Ok, I swapped out the solenoid and the new one did the same thing. It stuck closed after cranking and wouldn't open until removing the battery cable. So, I started experimenting and found that removing the wire (marked with blue X below) going from the "I" post to Coil+ solved the issue:



Which makes sense when I think about it since "I" holds the solenoid open. And if the output of the relay feeds back into "I" it will not close. Do you have that part wired up in yours?